Tank type or canister vacuum cleaners have long been known in the art. Such vacuum cleaners typically comprise a canister assembly housing both a suction generator and a dirt collection vessel. Typically the canister assembly includes wheels or rollers which function to allow the operator to smoothly pull the canister assembly across a floor while cleaning. A cleaning wand and cooperating flexible hose are attached to the canister assembly for sucking up dirt and dust.
Since the hose typically has a fixed length, when a canister vacuum cleaner is utilized to clean stairways, the canister assembly must be either supported on a stair or held by the operator. Unfortunately, most canister vacuum cleaners cannot be stabily supported on a stair due to their size and shape as well as the presence of the movable wheels or rollers that serve to move the vacuum cleaner across a floor during use. Further, it is inconvenient and awkward for the operator to hold the canister assembly during a stair cleaning operation as this leaves only one hand to manipulate the wand.
As such, some efforts have been made in the past to address this difficulty. For example, U.S. Pat. No. 3,881,535 to Du Bois et al. discloses a canister vacuum cleaner incorporating a pair of pawls, each including a sloping cam surface at the outer end thereof to engage in cavities in the rear wheels of the vacuum cleaner. The pawls prevent rotation of those wheels and help stabilize the vacuum cleaner on a stairway as best illustrated in FIG. 1 of that patent.
U.S. Pat. No. 3,820,808 to Brunning et al. discloses a canister vacuum cleaner equipped with a lock crank including caps of resilient material that engage the rear tires or wheels of the canister assembly to hold the canister assembly on a stairway. Neither Brunning et al. or Du Bois et al., however, teach the stabilizing of forward caster wheels that have both pivoting and rotational motion. As such, both cleaners tend to shift near their front side when in an inclined position.
U.S. Pat. No. 5,937,477 to Dyson discloses a canister vacuum cleaner sized and shaped so that the canister assembly may be positioned stabily on a flight of stairs. Many consumers, however, could find the unusual shape of this device objectionable.
Accordingly, a need exists in the art for a novel, more effective and efficient way to stabilize a canister assembly on a stairway, while still maintaining a traditional appearance, so that both hands of the operator are free to complete the cleaning operation. In addition, a further need exists for effectively stabilizing caster wheels having both pivoting and rotational motion.